This application claims the priority of Japanese patent document 11-228444, filed 12 Aug. 1999, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an engine control device, and especially relates to an engine control device for screening an integrated circuit implemented in a circuit board.
Conventionally in a semiconductor integrated circuit for an engine control device of a vehicle, a chip which is cut out from a wafer is screened after having been protected by a package; and after any initial failure in the form of a latent defect is removed from the integrated circuit, the chip is mounted on a circuit board.
Recently, in semiconductor integrated circuits the integrated circuit is mounted on a circuit board in bare chip form (without using the package), in order to reduce mounting size or area, to improve electrical characteristics, and to achieve reduction of manufacturing cost.
In this case, it is not efficient (a lot of time is needed) to individually screen each integrated circuit which is in bare chip form before mounting it on the circuit board, and it is expected to screen the integrated circuit after mounting it.
In the conventional equipment for screening an integrated circuit in bare chip form on a circuit board, a voltage regulator is provided in the circuit board. When a voltage changeover signal is generated by a communication signal from an outside communications means, the voltage occurring in the resistor is amplified to a high voltage (burn-in voltage) by amplifier circuitry, and screening is performed by adding such high voltage in the integrated circuit. (For example, Japanese Patent Laid-open No. 09-304481 and 10-009041 are referred to).
In Japanese Patent Laid-open No. 09-304481 bulletin, it is disclosed to screen by adding a burn-in voltage on the integrated circuit after mounting it, wherein the conventional equipment needs a voltage supervisory circuit and a communications means other than a voltage regulator having a resistor, an amplifier, etc. Thus, the constitution thereof becomes complicated, and no attention is given to reduction of manufacturing cost by reducing the number of components and the number of production steps as a characteristic feature, to mount the chip on the circuit board in bare chip form.
Furthermore, in a technique disclosed in Japanese Patent Laid-open No. 10-009041 bulletin, although no external communications means external is needed. Constitution of the voltage regulator and said voltage supervisory circuit are the same. Moreover, Japanese Patent Laid-open No. 09-304481 bulletin does not disclose anything relating to the reduction of the manufacturing cost.
Based on the above prior art, one object of the present invention is to provide an engine control device having a voltage adjustment which includes screening of a semiconductor integrated circuit mounted on a circuit board in bare chip form (so as to reduce a mounting area thereof).
Another object of the invention is to improve electric characteristics of such an engine control device and reduce its manufacturing cost by providing a simple constitution.
In order to achieve the above-stated object, an engine control device according to the present invention comprises an integrated circuit (such as an arithmetic processing unit etc.) for processing operation of control programs, and an output voltage adjustment circuitry to switch a rated voltage to screen said integrated circuit. According to the invention, the output voltage adjustment circuit comprises plural resistors provided between an output side power line (or the rated voltage) and ground.
Furthermore, according to the present invention the engine control device adds a voltage which is greater than that in normal operation on the integrated circuit when screening said integrated circuit. The output voltage adjustment circuitry is connected to another resistor connected to ground and a connecting point between the plural resistors is connected to the other resistor, and is connected to the constant voltage source circuitry which outputs the rated voltage to the integrated circuit.
The engine control device of the present invention constituted as stated above comprises output voltage adjustment circuitry to switch the rated voltage to screen the integrated circuit, the output voltage adjustment circuitry being constituted with three resistors at least. Accordingly, all integrated circuits can be screened after being mounted, by a low cost constitution without complicated circuitry; and it becomes possible to reduce manufacturing cost and to save time of screening.
Furthermore, in the engine control device of the present invention the other resistor is connected with ground by switching on/off.
Furthermore, in the engine control device of the present invention the other resistor is provided externally to said engine control device, or is connected to a connecting point between said plural resistors through a non-used terminal of said engine control device.
Furthermore, in the engine control device of the present invention the other resistor is internal to said engine control device, or switches on/off based on a serial communication signal.
Furthermore, in the engine control device of the present invention, the arithmetic processing unit has a storage device to be capable of rewriting said control program by said serial communication signal so as to switch on/off, or the arithmetic processing unit has a control program to switch over said rated voltage by said serial communication signal so as to switch on/off.
In the engine control device of the present invention constituted as above, as the program is rewritten with the serial communication signal or is constituted to be switched, all integrated can be screened after being mounted even when no unused terminal is provided.
Furthermore, the control device according to the present invention comprises an integrated circuit such as an arithmetic processing unit etc. for processing operation of control programs, an output voltage adjustment means to switch a rated voltage to screen integrated circuit, and a check means to examine characteristics of said arithmetic processing unit and said integrated circuit.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.